Daylight visible dyes have been employed to detect leaks in refrigeration systems utilizing fluorocarbon refrigerants and refrigeration oils. At the site of the leak, the escaping refrigerants and refrigeration oils containing visible dyes are detectable in normal light to a slight extent depending on the size of the leak.
Traditionally, oil soluble azo and anthraquinone dyes have been used as leak detectors in fluorocarbon refrigerants. These dyes are insufficiently stable at high temperatures such as those produced in automotive and commercial refrigeration systems. Low solubility of these dyes in the refrigerants and refrigeration oils results in clumps of dye powders being circulated through the system. Such clumps may clog the refrigeration system.
U.S. Pat. No. 1,915,965 discloses a method of testing for leaks in a refrigeration system of the compression type. Basic daylight visible dyes, such as methyl violet base, crystal violet, auramine B, rhodamine B, etc., are disclosed for use as leak detectors in refrigeration systems. These basic dyes are unstable at high temperatures and may be converted to tars which plug the system. Such basic dyes also have a low solubility in widely used refrigeration oils.
U.S. Pat. No. 4,369,120 discloses anthraquinone blue dyes for use as visual leak detectors in refrigerants, refrigeration oils, and admixtures of both. These blue dyes are visual leak indicators which readily stain surrounding areas of a leak in a refrigeration system due to their intense blue color which is differentiable from leaks of other fluid systems; e.g., red fuel oil or other colored fluids in automotive systems. The problems with these blue dyes are inherent to all visible dyes as described above.